replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Revert "UBSan: Teach isDerivedFromAtOffset and findBaseAtOffset about vbases" 

This reverts commit r221445. This change leads to false positives
reports from -fsanitize=vptr. See original commit thread for more
details.

llvm-svn: 224972
This commit is contained in:
Alexey Samsonov 2014-12-30 00:33:50 +00:00
parent 5909ebcd6c
commit 93c064968d
2 changed files with 22 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
compiler-rt/lib/ubsan/ubsan_type_hash.cc
View File

@ -115,8 +115,7 @@ __ubsan::__ubsan_vptr_type_cache[__ubsan::VptrTypeCacheSize];
/// \brief Determine whether \p Derived has a \p Base base class subobject at
/// offset \p Offset.
static bool isDerivedFromAtOffset(sptr Object,
const abi::__class_type_info *Derived,
static bool isDerivedFromAtOffset(const abi::__class_type_info *Derived,
const abi::__class_type_info *Base,
sptr Offset) {
if (Derived->__type_name == Base->__type_name)
@ -124,7 +123,7 @@ static bool isDerivedFromAtOffset(sptr Object,
if (const abi::__si_class_type_info *SI =
dynamic_cast<const abi::__si_class_type_info*>(Derived))
return isDerivedFromAtOffset(Object, SI->__base_type, Base, Offset);
return isDerivedFromAtOffset(SI->__base_type, Base, Offset);
const abi::__vmi_class_type_info *VTI =
dynamic_cast<const abi::__vmi_class_type_info*>(Derived);
@ -139,13 +138,13 @@ static bool isDerivedFromAtOffset(sptr Object,
sptr OffsetHere = VTI->base_info[base].__offset_flags >>
abi::__base_class_type_info::__offset_shift;
if (VTI->base_info[base].__offset_flags &
abi::__base_class_type_info::__virtual_mask) {
sptr VTable = *reinterpret_cast<const sptr *>(Object);
OffsetHere = *reinterpret_cast<const sptr *>(VTable + OffsetHere);
}
if (isDerivedFromAtOffset(Object + OffsetHere,
VTI->base_info[base].__base_type, Base,
Offset - OffsetHere))
abi::__base_class_type_info::__virtual_mask)
// For now, just punt on virtual bases and say 'yes'.
// FIXME: OffsetHere is the offset in the vtable of the virtual base
// offset. Read the vbase offset out of the vtable and use it.
return true;
if (isDerivedFromAtOffset(VTI->base_info[base].__base_type,
Base, Offset - OffsetHere))
return true;
}
@ -154,15 +153,14 @@ static bool isDerivedFromAtOffset(sptr Object,
/// \brief Find the derived-most dynamic base class of \p Derived at offset
/// \p Offset.
static const abi::__class_type_info *
findBaseAtOffset(sptr Object, const abi::__class_type_info *Derived,
sptr Offset) {
static const abi::__class_type_info *findBaseAtOffset(
const abi::__class_type_info *Derived, sptr Offset) {
if (!Offset)
return Derived;
if (const abi::__si_class_type_info *SI =
dynamic_cast<const abi::__si_class_type_info*>(Derived))
return findBaseAtOffset(Object, SI->__base_type, Offset);
return findBaseAtOffset(SI->__base_type, Offset);
const abi::__vmi_class_type_info *VTI =
dynamic_cast<const abi::__vmi_class_type_info*>(Derived);
@ -174,13 +172,12 @@ findBaseAtOffset(sptr Object, const abi::__class_type_info *Derived,
sptr OffsetHere = VTI->base_info[base].__offset_flags >>
abi::__base_class_type_info::__offset_shift;
if (VTI->base_info[base].__offset_flags &
abi::__base_class_type_info::__virtual_mask) {
sptr VTable = *reinterpret_cast<const sptr *>(Object);
OffsetHere = *reinterpret_cast<const sptr *>(VTable + OffsetHere);
}
if (const abi::__class_type_info *Base = findBaseAtOffset(
Object + OffsetHere, VTI->base_info[base].__base_type,
Offset - OffsetHere))
abi::__base_class_type_info::__virtual_mask)
// FIXME: Can't handle virtual bases yet.
continue;
if (const abi::__class_type_info *Base =
findBaseAtOffset(VTI->base_info[base].__base_type,
Offset - OffsetHere))
return Base;
}
@ -232,8 +229,7 @@ bool __ubsan::checkDynamicType(void *Object, void *Type, HashValue Hash) {
return false;
abi::__class_type_info *Base = (abi::__class_type_info*)Type;
if (!isDerivedFromAtOffset(reinterpret_cast<sptr>(Object), Derived, Base,
-Vtable->Offset))
if (!isDerivedFromAtOffset(Derived, Base, -Vtable->Offset))
return false;
// Success. Cache this result.
@ -247,9 +243,8 @@ __ubsan::DynamicTypeInfo __ubsan::getDynamicTypeInfo(void *Object) {
if (!Vtable)
return DynamicTypeInfo(0, 0, 0);
const abi::__class_type_info *ObjectType = findBaseAtOffset(
reinterpret_cast<sptr>(Object),
static_cast<const abi::__class_type_info *>(Vtable->TypeInfo),
-Vtable->Offset);
static_cast<const abi::__class_type_info*>(Vtable->TypeInfo),
-Vtable->Offset);
return DynamicTypeInfo(Vtable->TypeInfo->__type_name, -Vtable->Offset,
ObjectType ? ObjectType->__type_name : "<unknown>");
}

3
compiler-rt/test/ubsan/TestCases/TypeCheck/vptr.cpp
View File

@ -48,8 +48,7 @@ struct T : S {
virtual int v() { return 1; }
};
struct X {};
struct U : S, T, virtual X { virtual int v() { return 2; } };
struct U : S, T { virtual int v() { return 2; } };
struct V : S {};